Great Lens!
I got this lens to replace my 400 2.8L VI. I really like this lens but I have to say I cannot see a real big improvement over the IQ, between VI and VII. If I had to do it all over again, I may have kept my VI. I am not unhappy at all with the upgrade, I just may have been expecting to much. Still a great lens and would recommend it to anyone.
January 28, 2014

THE BEST CANON LENS EVER MADE
It is an excellent lens! I use it with my Canon EOS-1D X camera. Actually I have some Canon L series lenses such as Canon EF 200mm f/2L IS USM, Canon EF 24-70mm f/2.8l IS II USM, Canon EF 85mm f/1.2l II USM, Canon EF 14mm f/2.8l II USM, Canon EF 100mm f/2.8l IS USM, Canon EF 70-200mm f/2.8l II IS USM and of course my new Canon EF 400mm f/2.8l II USM. I use my another lovely camera Canon EOS-5D Mark III. I like this new lens very much! The picture quality is excellent!
November 24, 2012

Outstanding Performance
The Canon 400 mm f 2.8 MK II is outstanding in all aspects. The f 2.8 opening provides superb images wide open, the weight has been significantly reduced allowing for its handheld use for photographing birds in flight for up 3-4 hour (personal limits). It weight reduction also is a great advantage when carrying in the field with a tripod. I use this lens with the 5DIII and the autofocus performance is incredible delivering a 95-98% of in-focus images. When used with a 1.4X Canon MKIII image quality degradation is not noticed. I replaced the foot with one that provides a lower height profile, lighter weight and a built-in groove for mounting to ballheads without the need to use a mounting plate.
September 8, 2012

AWESOME LENS!
I have many lenses in my line up but this lens paired with a 5d3 or a 1dx is absolutely remarkable. Would recommend it to ANYONE. Don't let the price scare you away. Use it once and you will be hooked!
August 7, 2012